The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:                ALD atomic layer deposition        ASIC application specific integrated circuit        BOX buried oxide        CMOS complimentary MOS        DT deep trench        DT capacitor deep trench capacitor        DRAM dynamic random access memory        eDRAM embedded dynamic random access memory        eSRAM embedded static random access memory        FET field effect transistor        Epi epitaxial growth        FiN fin-type        FinFET fin-type FET        IC integrated circuit        MOSFET metal-oxide-semiconductor FET        PDSOI partially depleted SOI        RF radio frequency        RIE reactive ion etching        SCE short channel effect        SOI semiconductor on insulator        SRAM static random access memory        STI shallow trench isolation        TTO trench top oxide        UTBB ultra thin body and box        UT Box ultra thin box        
The growing gap between on-chip gates and off-chip I/O bandwidth argues for larger amounts of on-chip memory. Embedded DRAM, a capacitor-based dynamic random-access memory may be integrated on the same integrated circuit (IC) as an ASIC (application specific IC) or a processor. The cost-per-bit may be higher than for stand-alone DRAM chips but in many applications the performance advantages of placing the eDRAM on the same chip as the processor outweighs the cost disadvantage compared with external memory.
Embedding memory on the ASIC or processor allows for much wider busses and higher operation speeds, and due to much higher density of DRAM in comparison to SRAM, larger amounts of memory can be installed on smaller chips if eDRAM is used instead of eSRAM.
Deep trenches, typically having a depth exceeding one micron in contrast to shallow trenches having a depth less than one micron, are employed in the semiconductor industry to provide a variety of useful devices including a deep trench capacitor. The deep trenches may be utilized in a stand-alone semiconductor circuit such as a dynamic random access memory (DRAM) circuit to provide deep trench capacitors, or may be utilized as an embedded circuit component of a semiconductor chip that also includes other semiconductor circuits such as a processor core or other logic circuits. Particularly, embedded capacitors employing a deep trench are employed to enable an embedded memory device, e.g., an embedded dynamic random access memory (eDRAM) cell, a passive component of a radio frequency (RF) circuit, and decoupling capacitors that provide a stable voltage supply in a semiconductor circuit.
Semiconductor-on-insulator (SOI) substrates are employed in the semiconductor industry for performance benefits due to reduced capacitive coupling between semiconductor devices and the bulk portion of the substrate provided by a buried insulator layer. High performance logic chips are frequently manufactured on an SOI substrate to provide enhanced performance over devices having comparable dimensions and manufactured on a bulk substrate. Incorporation of embedded capacitors into the SOI substrate, however, requires not only formation of deep trenches in the SOI substrate but also formation of a buried plate beneath a buried insulator layer, while preventing diffusion of dopants into a top semiconductor layer above the buried insulator layer.